Thermally processed media are widely used in a variety of applications, such as in the medical, industrial and graphic imaging fields. For example, medical laser imagers reproduce diagnostic images on thermally processed photothermographic film. After exposure, the film is thermally developed by means of a heated member, such as a rotatable heated drum. Subsequently, the developed media is cooled to prevent over development of the image and to allow a user to hold the media while examining the developed image.
During the cooling process, it is important to cool the media uniformly to avoid image artifacts that could interfere with diagnosis. Film cooling is also required to protect various electronics components in the laser imager from overheating. Various active cooling systems have been proposed using forced convection where moving air directly contacts the heated media. (See: U.S. Pat. No. 5,557,388, issued Sep. 17, 1996, inventors Creutzmann et al.; U.S. Pat. No. 3,914,097, issued Oct. 21, 1975, inventor Wurl; U.S. Pat. No. 4,545,671, issued Oct. 8, 1985, inventor Anderson; U.S. Pat. No. 5,221,200, issued Jun. 22, 1993, inventors Roztocil et al.). These systems present problems resulting from uneven cooling which produces image artifacts.
A passive cooling system has also been used with great success. As disclosed in U.S. Pat. No. 5,563,681, issued Oct. 8, 1996, inventors Kirkwold et al., and U.S. Pat. No. 5,699,101 issued Dec. 16, 1997, inventor Allen, this system included a plate positioned adjacent the exit of a heated drum processor. In one arrangement, the plate has a first region adjacent the exit from the heated drum of thermally insulative material and a second successive region of thennally conductive material. In another arrangement, the plate has a textured and/or perforated top surface positioned relative to the heated drum so that the media slides on the top surface. Although the passive cooling systems disclosed in the latter two patents are successful for their intended purposes, in laser imager producing film at rates of 160 images per hour or more such systems are unable to handle the substantial increase in heat generated. The high throughput requires the cooling system to absorb proportionately more heat per unit of time, before the film encounters components in the imager that might produce image artifacts by non-uniformly cooling the film.
There is thus a need for a cooling system in high throughput laser imagers which maintains excellent image quality by uniformly cooling heated media processed by the laser imager.